Design Methodology of Camshaft Driven Charge Valves for Pneumatic Engine Starts

Michael M. Moser (1) , Christoph Voser (1) , Christopher H. Onder (1) , Lino Guzzella (1)

1 ETH Zürich - Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich]

Idling losses constitute a significant amount of the fuel consumption of internal combustion engines. Therefore, shutting down the engine during idling phases can improve its overall efficiency. For driver acceptance a fast restart of the engine must be guaranteed. A fast engine start can be performed using a powerful electric starter and an appropriate battery which are found in hybrid electric vehicles, for example. However, these devices involve additional cost and weight. An alternative method is to use a tank with pressurized air that can be injected directly into the cylinders to start the engine pneumatically. In this paper, pneumatic engine starts using camshaft driven charge valves are discussed. A general methodology for an air-optimal charge valve design is presented which can deal with various requirements. The proposed design methodology is based on a process model representing pneumatic engine operation. A design example for a two-cylinder engine is shown, and the resulting optimized pneumatic start is experimentally verified on a test bench engine. The engine’s idling speed of 1200 rpm can be reached within 350 ms for an initial pressure in the air tank of 10 bar. A detailed system analysis highlights the characteristics of the optimal design found.

Domaines: Physique [physics]

Michael M. Moser, Christoph Voser, Christopher H. Onder, Lino Guzzella. Design Methodology of Camshaft Driven Charge Valves for Pneumatic Engine Starts. Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles, 2015, 70 (1), pp.179-194. ⟨10.2516/ogst/2013207⟩. ⟨hal-01931291⟩